A mobile communication system specified in 3GPP, for example, a mobile communication system of an LTE (Long Term Evolution) scheme specifies a “CSG cell” wherein only a specific mobile station UE belonging to a “CSG (Closed Subscriber Group)” can be on standby or made accessible.
The CSG cell is assumed to provide an added value to the specific mobile station UE belonging to the CSG in the form of points such as charges, service, and QoS (Quality of Service).
The CSG cell informs a “CSG-ID” and the mobile station UE holds the list of the CSG “Allowed CSG List” having access rights. The mobile station UE receives broadcast information of the cell which is detected by searching the cell and determines whether it can be accessed or stand by in the corresponding cell by determining whether or not the “CSG-ID” included in the broadcast information is included in the “Allowed CSG List”.
Furthermore, in the LTE mobile communication system, it is presumed that a mobile station UE being connected measures neighbouring cells, transmits a “Measurement Report” related to the neighbouring cells to a radio base station eNB, and based on the measurement report, the radio base station eNB, to which the mobile station UE is connected, performs handover control by determining the necessity of handover.
However, there is a problem in the mobile communication system where the radio access network fails in the handover because the mobile station UE cannot access the CSG cell though the mobile station which starts the handover process to the corresponding CSG cell on the basis of the “Measurement Report” received from the mobile station UE which does not belong to the CSG of the specific CSG cell and the resources get used unnecessarily as a result.